Sensor using ultra thin waveguides and optical fibers

Methods and apparatus are provided for detecting one or more contaminant particles in an environment with an optical sensor. The sensor includes at least one optical waveguide in a resonant arrangement and a light source positioned in an environment in which the presence of a contaminant particle is sought to be determined. The at least one optical waveguide is of a diameter that an evanescent tail of the lightwave extending there through extends into the environment and is reactive to at least one contaminant particle in the surrounding environment. A detector is positioned to receive light indicative of the sharpness of the optical resonance lineshape of the optical resonator at a pre-selected optical wavelength. The detected information determines the specific contaminant particle in the environment and the concentration of the contaminant particle in the environment.